Weather not the only headwind: BlackRock pro

The weather isn't the only thing dogging the U.S. economy lately, BlackRock's chief investment strategist told CNBC on Friday.

The other major culprit? A need for disposable income growth, according to BlackRock's Russ Koesterich.

"The reality is that in the long term, the economy needs to generate top-line growth, and for the economy to grow faster the consumer needs to spend faster," Koesterich said on "Squawk on the Street." "If income is constrained, it's going to be hard to see that expected pickup in consumption. So to me that's the linchpin of this."

A batch of fresh weaker-than-expected economic data released Friday left U.S. stocks mixed, a day after disappointing retail numbers.

"I would have to say I'm surprised how much the market has looked past things like the retail sales data, which to some extent was impacted by the weather," Koesterich said. "But to my mind, a better explanation for that number was very weak income growth, which is not weather related."

Luciano Siracusano, chief investment strategist with WisdomTree Investments, said investors should ask two important questions about the economy: How healthy is corporate America? And how temporary was the cold weather's effect on economic growth?

"Personal income is at an all time high," Siracusano told CNBC. "Personal spending is at an all time high. GDP is at an all time high. And you haven't gotten back to all time highs in employment, which means the economy is still being productive. It's just not growing as fast as it has in the past."

—By CNBC's Jeff Morganteen. Follow him on Twitter at @jmorganteen and get the latest stories from "Squawk on the Street."